Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts

The use of heterogeneous catalysts for biodiesel production is known to mitigate technical issues associated with the use of homogeneous catalysts which are contributed mainly by costly separations and purification steps. However, the limitation in catalytic active sites and stability are issu...

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Main Author:	Mavakumba, Kefas Haruna
Format:	Thesis
Language:	English
Published:	2018
Subjects:	Biodiesel fuels Fatty acids Heterogeneous catalysis
Online Access:	http://psasir.upm.edu.my/id/eprint/77317/1/FK%202019%2013%20UPMIR.pdf
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spelling	my-upm-ir.773172022-01-28T08:06:35Z Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts 2018-11 Mavakumba, Kefas Haruna The use of heterogeneous catalysts for biodiesel production is known to mitigate technical issues associated with the use of homogeneous catalysts which are contributed mainly by costly separations and purification steps. However, the limitation in catalytic active sites and stability are issues that deter the effectiveness of the heterogeneous system. In principle, the sugar carbon based catalysts can address these problems. In this study, sulfonated carbonized glucose catalyst was synthesized and utilized for biodiesel synthesis through a single step esterification of non-edible palm fatty acid distillate (PFAD) in an oscillatory flow reactor (OFR). The optimum sulfonation conditions obtained from the use of RSM-CCRD in the catalyst synthesis were 11.25 % of (NH4)2SO4 concentration, 5.34 hr of time, 25.16 ml of concentrated H2SO4 and 151.15 oC of temperature which achieved 93.30 % free fatty acid (FFA) conversion and 91.87 % FAME yield. The optimized sulfonated catalyst underwent detailed characterization utilizing FTIR, XRD, TGA, TPD-NH3, FESEM, EDX and BET. Results showed it had a stable amorphous polycyclic aromatic structure with BET surface area of 4.47 m2/g and 5.92 mmol/g acid sites density thereby exhibiting high catalytic activity in the esterification reaction. The optimization of process conditions in the batch reactor achieved 93.23 % FFA conversion at optimized conditions of 4 wt.% of sulfonated catalyst, 65 oC reaction temperature, 10:1 methanol to PFAD molar ratio and 4 h of reaction time. The catalyst was active up to five cycles re-uses without reactivation. The kinetics study of the esterification of PFAD and methanol using the sulfonated glucose acid catalyst performed in the batch reflux reactor proved that it was an irreversible reaction due to the use of excess methanol. The experimental data was best interpreted with bimolecular (equimolar) second order model. The rate constant of the reaction (k) from the kinetics study determined at various temperatures ranged from 0.0002 to 0.00053 and the activation energy was calculated to be 55.08 kJmol- 1. The developed kinetics model and the experimental data are in good agreement. The biodiesel production with optimized solid acid catalyst in OFR was successfully performed. The OFR achieved maximum of 97.1 % FFA conversion to FAME and >94 % yield. The optimum operating conditions at optimum conversion were 2.5 wt.% of sulfonated catalyst, 60 oC temperature, 9:1 methanol to PFAD molar ratio, 6 Hz oscillation frequency, and 50 min reaction time. The sulfonated catalyst showed reasonable catalytic activity for up to four cycle’s reuse in the OFR achieving about 80 % conversion at the fourth cycle. The performance of OFR was better than the reflux batch reactor in terms of conversion and operating conditions due to the efficient fluid mixing mechanism which resulted in reaction time reduction as well as enhancing heat and mass transfer. In addition, the properties of the PFAD FAME produced from the OFR showed a pour point and cloud point of 12 oC and 15 oC, respectively. The low temperature characteristics of the biodiesel were slightly above the ASTM standard due to high FFA constituent of the PFAD. Most of the other properties are within standard specifications for ASTM D6751 and EN 14214. The biodiesel produced is not suitable for winter grade biodiesel due to its high pour point. In conclusion, the synthesized modified sulfonated glucose catalyst has proven to be a catalytically active and stable heterogeneous acid catalyst for biodiesel synthesis from high FFA PFAD feedstock especially in the OFR system. Biodiesel fuels Fatty acids Heterogeneous catalysis 2018-11 Thesis http://psasir.upm.edu.my/id/eprint/77317/ http://psasir.upm.edu.my/id/eprint/77317/1/FK%202019%2013%20UPMIR.pdf text en public doctoral Universiti Putra Malaysia Biodiesel fuels Fatty acids Heterogeneous catalysis Yunus, Robiah
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English
advisor	Yunus, Robiah
topic	Biodiesel fuels Fatty acids Heterogeneous catalysis
spellingShingle	Biodiesel fuels Fatty acids Heterogeneous catalysis Mavakumba, Kefas Haruna Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
description	The use of heterogeneous catalysts for biodiesel production is known to mitigate technical issues associated with the use of homogeneous catalysts which are contributed mainly by costly separations and purification steps. However, the limitation in catalytic active sites and stability are issues that deter the effectiveness of the heterogeneous system. In principle, the sugar carbon based catalysts can address these problems. In this study, sulfonated carbonized glucose catalyst was synthesized and utilized for biodiesel synthesis through a single step esterification of non-edible palm fatty acid distillate (PFAD) in an oscillatory flow reactor (OFR). The optimum sulfonation conditions obtained from the use of RSM-CCRD in the catalyst synthesis were 11.25 % of (NH4)2SO4 concentration, 5.34 hr of time, 25.16 ml of concentrated H2SO4 and 151.15 oC of temperature which achieved 93.30 % free fatty acid (FFA) conversion and 91.87 % FAME yield. The optimized sulfonated catalyst underwent detailed characterization utilizing FTIR, XRD, TGA, TPD-NH3, FESEM, EDX and BET. Results showed it had a stable amorphous polycyclic aromatic structure with BET surface area of 4.47 m2/g and 5.92 mmol/g acid sites density thereby exhibiting high catalytic activity in the esterification reaction. The optimization of process conditions in the batch reactor achieved 93.23 % FFA conversion at optimized conditions of 4 wt.% of sulfonated catalyst, 65 oC reaction temperature, 10:1 methanol to PFAD molar ratio and 4 h of reaction time. The catalyst was active up to five cycles re-uses without reactivation. The kinetics study of the esterification of PFAD and methanol using the sulfonated glucose acid catalyst performed in the batch reflux reactor proved that it was an irreversible reaction due to the use of excess methanol. The experimental data was best interpreted with bimolecular (equimolar) second order model. The rate constant of the reaction (k) from the kinetics study determined at various temperatures ranged from 0.0002 to 0.00053 and the activation energy was calculated to be 55.08 kJmol- 1. The developed kinetics model and the experimental data are in good agreement. The biodiesel production with optimized solid acid catalyst in OFR was successfully performed. The OFR achieved maximum of 97.1 % FFA conversion to FAME and >94 % yield. The optimum operating conditions at optimum conversion were 2.5 wt.% of sulfonated catalyst, 60 oC temperature, 9:1 methanol to PFAD molar ratio, 6 Hz oscillation frequency, and 50 min reaction time. The sulfonated catalyst showed reasonable catalytic activity for up to four cycle’s reuse in the OFR achieving about 80 % conversion at the fourth cycle. The performance of OFR was better than the reflux batch reactor in terms of conversion and operating conditions due to the efficient fluid mixing mechanism which resulted in reaction time reduction as well as enhancing heat and mass transfer. In addition, the properties of the PFAD FAME produced from the OFR showed a pour point and cloud point of 12 oC and 15 oC, respectively. The low temperature characteristics of the biodiesel were slightly above the ASTM standard due to high FFA constituent of the PFAD. Most of the other properties are within standard specifications for ASTM D6751 and EN 14214. The biodiesel produced is not suitable for winter grade biodiesel due to its high pour point. In conclusion, the synthesized modified sulfonated glucose catalyst has proven to be a catalytically active and stable heterogeneous acid catalyst for biodiesel synthesis from high FFA PFAD feedstock especially in the OFR system.
format	Thesis
qualification_level	Doctorate
author	Mavakumba, Kefas Haruna
author_facet	Mavakumba, Kefas Haruna
author_sort	Mavakumba, Kefas Haruna
title	Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
title_short	Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
title_full	Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
title_fullStr	Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
title_full_unstemmed	Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts
title_sort	biodiesel synthesis from pfad using heterogeneous sulfonated-glucose catalysts
granting_institution	Universiti Putra Malaysia
publishDate	2018
url	http://psasir.upm.edu.my/id/eprint/77317/1/FK%202019%2013%20UPMIR.pdf
_version_	1747813216054935552

Biodiesel synthesis from PFAD using heterogeneous sulfonated-glucose catalysts

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